Hydraulic punch press with mechanism for adjusting stripper

ABSTRACT

The punch is surrounded by a tubular housing carrying a stripper plate. To adjust the stripper plate, vertically, provision is made of compactly nested threaded rings. Angularly, provision is made of an adjusting mechanism which acts on a rod projecting from the upper end of a hydraulic cylinder and connected to a downwardly projecting ram for reciprocating the punch.

United States Patent 11 1 Scott et a1. 1 1 Nov. 5, 1974 [5 1 HYDRAULIC PUNCH PRESS WITH 1,723,106 8/1929 Wigleuda 83/146 MECHANISM FOR ADJUSTING pp 2,541,772 2/1951 Lockard 83/146 Inventors: William B. Scott, Steward; Roger V.

Sawvell, New Milford, both of 111.

Assignee: W. A. Whitney Corp, Rockford, 111.

Filed: Feb. 13, 1974 Appl. No.: 442,089

Division of Ser. No. 274,391, July 24, 1972, Pat. No.

U.S. Cl 83/146, 83/543, 83/639, 83/701, 83/D1G. 1 Int. Cl 826d 7/06, B27f 1/02 Field of Search 83/146, 145, 639, 543,

References Cited UNITED STATES PATENTS 11/1928 Hutchinson et a1 1. 83/146 Primary Examiner-Frank T. Yost Attorney, Agent, or Firm-W0lfc, Hubbard. Lcydig, Voit & Osann, Ltd.

[57] ABSTRACT The punch is surrounded by a tubular housing carrying a stripper plate. To adjust the stripper plate, vertically, provision is made of compactly nested threaded rings. Angularly, provisionis made oj an adjusting mechanism which acts on a rod projecting from the upper end of a hydraulic cylinder and connected to a downwardly projecting ram for reciprocating the punch.

3 Claims, 1 Drawing Figure HYDRAULIC PUNOI-I PRESS WITH MECHANISM FOR ADJUSTING STRIPPER This is a division, of application Ser. No. 274,391, filed July 24, 1972 now US. Pat. No. 3,805,658.

BACKGROUND OF THE INVENTION This invention relates to a punch press with a reciprocable punch which coacts with an underlying die to punch holes in an intervening workpiece. More particularly, the invention relates to a punch press of the type in which the punch is carried on the end of a ram anchored to a piston which is adapted to be reciprocated back and forth within a cylinder in response to the admission of pressure fluid alternately into opposite ends of the cylinder.

A punch press of the same general type as the present press in disclosed in Scott US. Pat. No. 3,720,125. In such a press, the punch reciprocates through a stripper plate which strips the workpiece from the punch as the latter is retracted out of the newly formed hole. The stripper plate is adjustable toward and away from the die to accommodate workpieces of different thicknesses and is carried on the end of a tubular housing which extends alongside and generally encloses the punch.

SUMMARY OF THE INVENTION The general aim of the present invention is to provide a press in which the vertical spacing between the die and the bottom of the cylinder is reduced so as to enable the use of a comparatively short ram which reduces bending stresses applied to the ram and the cylinder when lateral forces are exerted on the ram as the punch strikes the workpiece.

An important object of the invention is to decrease the aforementioned vertical spacing by providing beneath the cylinder a new and improved mechanism for adjusting the stripper plate vertically, the adjusting mechanism being more compact in a vertical direction than prior mechanisms of the same general type and thus reducing the encumbrance beneath the cylinder and enabling closer positioning of the cylinder to the die so as to permit the use of a shorter ram.

These and other objects and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The single FIGURE of the drawings is a fragmentary front elevation of a new and improved punch press embodying the novel features of the present invention, parts of the press being broken away and shown in section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in the drawings for purposes of illustration, the invention is embodied in a punch press It) in which a vertically recipro'cable punch 11 coacts with an underlying die 13 on the main support or bed 14 of the press to punch holes in an intervening workpiece 15. The specific press which has been illustrated is numerically controlled and is particularly suitable for performing high speed nibbling operations in which the punch nibbles away successive portions of the workpiece to form a contoured hole or to shape the edge of the workpiece.

In this instance, the punch 11 is carried in a suitable punch holder 15 attached to the lower end of a vertically reciprocable rod or ram 16 which forms part of a hydraulic actuator 17 having an upright cylinder 19 anchored to a horizontal support or mounting plate 20, the latter being rigid with the bed 14 and overhanging the die 13. The upper end of the :ram 16 is connected to the lower end of a piston 21 which is reciprocated upwardly and downwardly in response to pressure fluid being alternately admitted into and dumped from opposite ends of the cylinder under the control of a suitable valve (not shown).

Overlying the die I3 and disposed just above the workpiece I5 is a circular stripper plate 23 formed with a central hole 24 through which the punch lll reciprocates during a normal punching cycle. As the punch is retracted through its upstroke, the stationary stripper plate engages the workpiece and thus strips the workpiece from the punch. The stripper plate is mounted on the lower end of a tubular housing 27 which completely encloses the punch and which includes an access door 29. The door normally is closed but can be opened to the position shown to enable changing of the punch and stripper plate.

In accordance with the invention, extremely vertically compact mechanism is provided beneath the cylinder mounting plate 20 for adjusting the stripper housing 27 upwardly anad downwardly so as to enable vertical adjustment of the stripper plate 23 to accommodate workpieces of different thicknesses between the stripper plate and the die 13. As shown, the adjusting mechanism 70 comprises an inner ring 71 which is telescoped over the lower end portion of a cylindrical, sleeve-like nose 73 formed integrally with and depending from the cylinder 19. The nose projects downwardly through a hole 74 in the cylinder mounting plate 20 and slidably receives the ram 16 to help guide and rigidly support the latter during reciprocation of the punch 11.

The inner ring 71 is internally threaded with threads of one hand and is externally threaded with threads of equal pitch but of the opposite hand, the ring being threaded onto the cylinder nose 73 so as to move upwardly and downwardly on the nose when rotated. Rotation of the ring in this particular instance is effected by a reversible rotary fluid motor 7.5 which is advantageously supported above the cylinder mounting plate 20 and whose drive shaft 76 carries a pinion 77 positioned to mesh with a second pinion 79 on the upper end of an upright shaft 80 projecting downwardly through the cylinder mounting plate 20. A gear 81 is fastened to the shaft 80 immediately below the cylinder mounting plate and meshes with gear teeth 83 formed around the outer periphery of the ring 71 just above the external threads thereon. Thus, when the motor is energized, the shaft is rotated to turn the ring 71 and cause the latter to thread upwardly and downwardly on the cylinder nose 73.

Threaded onto the external threads of the inner ring 71 is a non-rotatable outer ring 85 which is connected to the stripper housing 27 by means of angularly spaced shear pins 86 extending radially between the stripper housing and the outer ring. If the punch 11 should happen to strike the stripper plate 23 during the downstroke of the punch, the shear pins 86 will fracture to allow the housing 27 to pull loose from the outer ring 85 and, as a result, the ram 16 can complete its downstroke and the housing 27 will not be damaged by the punch jamming against the stripper plate.

To prevent rotation of the stripper housing 27 and the outer ring 85, a radially projecting bracket 87 is attached rigidly to the outer ring and is formed with a hole 88 which slidably and rotatably receives the lower end portion of the shaft 80. Thus, the shaft is free to rotate within the bracket but prevents turning of the outer ring 85 and permits the latter to move upwardly and downwardly.

With the foregoing arrangement, lowering of the stripper plate 23 is effected by driving the motor 75 in one direction so as to turn the inner ring 71 anad cause the latter to thread downwardly on the cylinder nose 73. The outer ring 85 and the stripper housing 27 are carried downwardly with the inner ring and, being held against rotation, the outer ring also threads downwardly on the inner ring. Accordingly, the stripper housing 27 and the stripper plate 23 are shifted downwardly through a distance which is twice as great as the downward displacement of the inner ring 71. Upward adjustment of the stripper plate is carried out in a similar manner by driving the motor in the opposite direction to cause the rings to thread upwardly.

As a result of the two threaded rings 71 and 85, the stripper plate 23 may be lowered through small increments and over a relatively wide range by moving the inner ring only a short distance downwardly from the cylinder mounting plate 20. Because the outer ring 85 is threaded onto the inner ring 71, the two rings are nested radially not only with one another but also with the cylinder nose 73 and thus the adjusting mechanism 70 is very compact in a vertical direction. Such compactness enables a reduction in the vertical distance between the die 13 and the bottom of the cylinder mounting plate 20 to permit the use of a comparatively short ram 16. The short ram thus is less likely to deflect laterally under the lateral forces exerted on the ram as the punch 11 impacts against the workpiece 15 during the nibbling operation and, in addition, lateral forces of smaller magnitude are transmitted back to the cylinder 19 by the ram. Accordingly, theh ram itself is comparatively rigid and remains rigidly supported in the cylinder.

We claim as our invention:

1. A punch press having a vertically reciprocable punch adapted to coact with an underlying die to punch a hole in an intervening workpiece, said press comprising a generally horizontal support plate, a cylinder mounted on the upper side of said support plate and having a depending nose projecting downwardly through a hole in the support plate, a piston slidable upwardly and downwardly within said cylinder, a ram pro- 10 jecting downwardly from said piston and through said nose and guided for up and down sliding by said nose, said punch being carried on the lower end of said ram, a stripper plate overlying said die and formed with a hole through which said punch reciprocates, and means mounting said stripper plate for vertical adjustment toward and away from said die, said means comprising a first ring having internal threads of one hand threaded onto said nose whereby the ring moves vertically on the nose in response to being rotated, a second ring connected to said stripper plate and having internal threads of the opposite hand threaded onto said first ring, and mechanism extending between said support plate and said second ring for preventing rotation of the second ring while allowing the latter to move vertically in the same direction as said first ring when the first ring is rotated.

2. A punch press as defined in claim 1 further including a reversible rotary motor mounted on the upper side of said support plate, a shaft projecting downwardly through said support plate and connected to be rotated by said motor, a gear fast on the lower end portion of said shaft and meshing with the outer periphery of said first ring to rotate the latter in response to rotation of said shaft, said means including a bracket connected to said second ring and slidably receiving said shaft.

3. A punch press as defined in claim 1 further including a stripper housing extending downwardly alongside said punch and carrying said stripper plate on its lower end, and shear pins connecting said stripper housing to said second ring and adapted to fracture and allow said stripper housing to break away from said second ring in the event said punch impacts against said stripper plate. 

1. A punch press having a vertically reciprocable punch adapted to coact with an underlying die to punch a hole in an intervening workpiece, said press comprising a generally horizontal support plate, a cylinder mounted on the upper side of said support plate and having a depending nose projecting downwardly through a hole in the support plate, a piston slidable upwardly and downwardly within said cylinder, a ram projecting downwardly from said piston and through said nose and guided for up and down sliding by said nose, said punch being carried on the lower end of said ram, a stripper plate overlying said die and formed with a hole through which said punch reciprocates, and means mounting said stripper plate for vertical adjustment toward and away from said die, said means comprising a first ring having internal threads of one hand threaded onto said nose whereby the ring moves vertically on the nose in response to being rotated, a second ring connected to said stripper plate and having internal threads of the opposite hand threaded onto said first ring, and mechanism extending between said support plate and said second ring for preventing rotation of the second ring while allowing the latter to move vertically in the same direction as said first ring when the first ring is rotated.
 2. A punch press as defined in claim 1 further including a reversible rotary motor mounted on the upper side of said support plate, a shaft projecting downwardly through said support plate and connected to be rotated by said motor, a gear fast on the lower end portion of said shaft and meshing with the outer periphery of said first ring to rotate the latter in response to rotation of said shaft, said means including a bracket connected to said second ring and slidably receiving said shaft.
 3. A punch press as defined in claim 1 further including a stripper housing extending downwardly alongside said punch and carrying said stripper plate on its lower end, and shear pins connecting said stripper housing to said second ring and adapted to fracture and allow said stripper housing to break away from said second ring in the event said punch impacts against said stripper plate. 